The present invention provides an improvement to the basic disc drive spindle motor in which ball bearings are utilized to journal a rotor about a shaft in a spindle motor. The embodiments of the present invention are designed to incorporate a magnetic bearing and spindle permanent magnet in a disc drive providing for a unique application of the known technology to improve disc drive motor performance.
Traditionally, disc drive designers have utilized conventional mechanical ball bearing assemblies as a means of rotatably journaling drive components. However, the use of conventional ball bearing assemblies in conjunction with high rotational speed devices has evidenced problems which are deleterious to drive system performance. Specifically, conventional mechanical bearings used are subject to metal wear, vibration/shock and friction problems. In order to alleviate the problems associated with conventional mechanical bearings, magnetic bearings may be substituted, thereby improving overall system performance. The use of magnetic bearings to improve disc drive system performance was disclosed in the concurrently filed U.S. patent application Ser. No. 08/201,676, filed Feb. 25, 1994 entitled "Passive Magnetic Bearings for a Spindle Motor" by Dunfield et al., and is expressly incorporated herein by reference.
Spindle motors and the use of permanent and electromagnets in a disc drive is well known in the art. The combination of a permanent magnet attached to a rotor interacting with an electromagnet assembly attached to a fixed stator as a means of journaling a disc about a stationary shaft is well known in the art. In the prior art, spindle permanent magnets served only as a means for rotating the rotor about the stator via an axial pivot. Separate means for maintaining the physical relationship between the rotor and the stator, namely conventional ball bearing systems, were previously employed. These separate means required extra space considerations, additional piece parts, lubricants and contributed to the overall manufacturing cost of the final product.
In the competitive disc drive industry, the optimization of the size of each component directly leads to smaller overall footprint for disc drives. Disc drive size, cost and performance are benchmarks for comparison in the industry. As such, process and design improvements which tend to integrate components and or component functions would be well received in the industry.